Was the land where Hiroshima city locates under the water?

As you can see on the Google maps, the center of the Hiroshima city is on the river delta.

Back in 1589, Mori Terumoto, the grandson and successor of the warlord Mori Motonari started to build the Hiroshima Castle in the largest delta of those made up of 7 (currently, the reconstruction of the river made it 6) rivers.

In order to defend the castle from the enemy, a ditch called "hori -moat-" is usually built, and Hiroshima Castle was built by using rivers as its moat.

The only moat that remains today is the inner-most moat, but if you walk around the city carefully, you can see stone pillars standing next to the moat on the sites of a building called a "yagura -tower-" that was built for the purpose of security.

As time passed, land reclamation progressed and the delta became a bustling city with people.

There are still some places where you can see the remnants of this history.